GSNW:
I'm looking for tips and hints, or pitfalls to avoid, in throwing an anniversary party for another couple.

DH has some very good friends that are coming up on their 15th wedding anniversary next year. They have been married longer than any of our other friends, because the bride was only 19 at the time of the wedding. The HC in question has been through a lot - they were expecting at the time of their wedding, they were obviously very young, and they have struggled financially in the past. They have made it to this point with two absolutely wonderful kids, overcome a lot of their obstacles, and really, are some of the nicest people we know. DH's best friend and his wife want to go in with us on throwing them a big celebration - of their family, their commitment, their accomplishments, etc.

I guess I really want to know what the best way is to go about throwing a party like this for someone else. I'm aware that they might want to celebrate privately as well, so we were thinking of doing a big shindig in their hometown and then gifting them with a fancy hotel suite for the night and breakfast in bed the next day, something along those lines. If your friends did something like this for you, what factors would you want considered?

Or would you prefer that your friends not horn in on your anniversary at all?

Lindee:
My first thought was is this going to set a precedent? Is everyone in your group going to get a big shindig and a fancy weekend for their 15th as it comes up? Will they feel obligated to chip in for lots of big celebrations over the next few years? It sounds a lovely and thoughtful idea but if it is only going to be for this deserving couple it sounds a little bit weird.

peaches:
Lindee makes a good point.

I would choose something simple for a 15th anniversary. I like the idea of the hotel suite for one night - or a bed and breakfast. That wouldn't need to be broadcast to everyone, it could be a private gift from you/DH and the other couple.

A casual barbecue or a houseparty (a drop-in or open house) would also be an option. That could be informal (the kids could participate) and not overly expensive.

Honestly, I wouldn't want a grand or formal affair at the 15 year mark. Maybe that's just me. I'd be thinking about other family members married longer who didn't have big shindigs. I'd also be worried about the expense; I wouldn't feel comfortable with friends doing something on a grand scale.

Thipu1:
Yes, this could open a real can of worms.

It's obvious that the OP really cares for and admires this couple, but there are questions.

How big is the 'big shindig' to be?

Will this be setting a precedent for 15th Anniversary parties in the OP's social group?

Will the couple to be honored be expected to reciprocate?

If the OP wants to provide the gift of a night at a hotel for the couple, it should be done as a private gift and not connected in any way to the party.

Does the couple really want a big'do?

After all, 15 years is a respectable age for a modern marriage but it isn't like a 25th or a 50th Anniversary. Usually, big blow-outs are arranged by the adult children of the couple. Since their children are 15 years-old at most, this isn't feasible in this case.

If a celebration is really wanted, I would go with something casual like a cook-out or a potluck with the approval of others who would be invited.

There are so many 'ifs' involved that I would seriously think twice or three times before making any plans.

NyaChan:
I think it is all in the presentation.

You want to celebrate your friends - that's great and very sweet! To avoid some pitfalls:

1) making them uncomfortable with your largesse (gifts if disproportionate to the relationship's closeness can be uncomfortable for the recipient - I mention this particularly because your post indicates that while this couple is lovely, they aren't your best friends)2) setting a precedent that might make others feel bad if they don't get the same3) creating a feeling of obligation on their part to reciprocate

Throw a party. Make it as casual or as fancy as you want. Mention that it coincides with their anniversary, but don't bill it as "We are throwing this big party just for these two!" and get them a nice cake to bring out to them come dessert time. If you have a gift you wish to give them, give it privately so that others don't feel as if they messed up by not having a gift or as if they are your audience. I think the hotel thing is a nice idea, but do consider:

1) whether they are even free on that day - so maybe just let them know that you would like to send them away for a night when it is convenient for them2) the children - are you covering babysitting for them while they are gone?